U.S. flag

An official website of the United States government, Department of Justice.

Prediction of Blood Back Spatter From a Gunshot in Bloodstain Pattern Analysis

NCJ Number
Date Published
20 pages
This article proposes a theoretical model for predicting and interpreting blood-spatter patterns resulting from a gunshot wound.
The physical process of generating a backward spatter of blood was linked to the Rayleigh-Taylor instability of blood accelerated toward the surrounding air, allowing the determination of the initial distribution of drop sizes and velocities. Then the motion of many drops in air was considered with governing equations accounting for gravity and air drag. Based on these equations, a numerical solution was obtained. It predicted the atomization process, the trajectories of the back-spatter drops of blood from the wound to the ground, the impact angle, and the impact Weber number on the ground, as well as the distribution and location of bloodstains and their shape and sizes. A parametric study was undertaken to predict patterns of backward blood spatter under realistic conditions corresponding to the experiments conducted in the present work. The results of the model were compared to the experimental data on back spatter generated by a gunshot impacting a blood-impregnated sponge. 1 table, 10 figures, and 44 references (publisher abstract modified)

Date Published: January 1, 2016